Prototyping 416
Additive manufacturing, as the name implies, manufactures parts by the addition of material in layers to a build area. Fused deposition modeling (also known as fused filament fabrication) is a subset of additive manufacturing in which a continuous filament of thermoplastic material is heated above its melting point, positioned, and then deposited in layers to craft a 3 dimensional part. In the more traditional configuration, FDM printers accomplish this by utilizing a drive gear that pulls material from a spool and forces it through a heated nozzle. Paired with stepper motors to position the build plate and this heated extrusion nozzle, 3D geometries are created. Utilizing the FDM printers at WSU for prototyping or for final components is an excellent manufacturing method that can be quick, relatively cheap, and easy. Despite this, the various printers at WSU all have their quirks, so understanding them and their differences is necessary to being able to utilize these machines to make products. At the time of this writing, the printers at WSU include 3 Stratasys U-Print FDM printers in the FIZ, as well as an air wolf axiom printer and a Raise 3D N2+ which are found in the Coug Shop. When choosing which 3D printer you will need to use there are a few considerations to make. Build size, dimensional accuracy, material, and cost are just some of these considerations. In terms of build size, the Raise 3D is the largest printer available. with a build volume of 12inx12inx24in, it offers the ability to create massive parts. Next, the Airwolf has a build volume of 8inx10inx10in. Finally, The fiz printers have the smallest volume of 8inx8inx6in. Remember that parts can be split and reformed to fit in the smaller printers. In terms of material, the U-Prints only utilize ABS with soluble support material. The Airwolf can use PLA or ABS and uses the same material for supports. The Raise 3D can only use PLA and also uses this for supports. There are various other novel types of 3D printing filament, such as metal, wood, or carbon fiber infused plastic filament, or even soft or elastic printing material. The Airwolf and the Raise 3D are the only printers that can take custom materials, but the Coug Shop staff should be contacted on these materials first. Dimensional accuracy and tolerance of parts varies between printers. The U-Prints in the FIZ are the best printers to use when small or critical details that may cause overhangs from the build plate are present. This is because they utilize soluble support material which can be dissolved away and leave excellent geometry. These printers also seem to have the best tolerances, followed by the Rasie 3D, and finally the Airwolf. It is recommended that if several parts need to fit together that they are all printed on the same printer. Small tolerances such as around 0.05" or 1.5 mm should be added to clearance fits. Cost is also a relevant factor when choosing which 3D printer to use. The U-Prints are advanced printers, and with that comes a very high cost. Both the Airwolf and Raise 3D are much cheaper in comparison. if a large part that doesn't have complex geometry is to be made it would be better to use these printers. The first step of preparing for 3D printing is the creation of a Solidworks or other CAD file, which needs to be saved as a .stl. This file will then be placed in a slicing software, which is what generates the code to tell the printer how to build your part. For the FIZ printers, FIZ staff will be able to help place and orient your part and create the Gcode file from the slicing software. The coug shop printers require a little more effort. You have control over parameters such as the orientation, speed of the printer, creation of supports and rafts, aong other things. It would be wise to seek guidance from the Coug Shop staff while creating the GCode for the printers. When in doubt run the printer at a slow speed (around 40-50 mm/s) and always use supports and a raft. CAD Notes: When designing a part which is intended for 3D printing, there are a few geometrical constraints to keep in mind: # Avoid overhangs which exceed 45 degrees if at all possible. Supports can of course be added, but this means either poor surface finish if the same material is used for the supports, or an increased chance of print failure if using a second nozzle for a separate support material. # Add fillets or champers for any surfaces which have an orthogonal intersection. Stress concentration at this points are larger than in an homogeneous material due to the presence of layer lines. # When developing your CAD model, try to design your model such that you have one flat surface to adhere to the print bed. You do not want an entirely rounded geometry, as this increases the change of a print coming off of the print bed, even with supports. # Keep in mind the print orientation when designing your part. There are plenty of white papers available on line which address this underrated but important point. # FEA analysis in Solidworks is not truly applicable to 3D printed parts as you're dealing with a non-homogeneous material. So when developing your part to factors of safety, keep in mind that you will need to look at much higher FOS than you planned for. Some Additional Notes: If making a prototype for a plastic mold, try using wood or foam as a substitute. Its cheaper, and is easier to work with. Scrap wood can be found at the shop in Dana, there are also various types of saws for cutting the wood. Talk to the shop attendants and they walk you through what needs to be done to cut the wood. With 3-D printing technology advancing and its popularity for prototyping increasing it would seem to be a valid and effective method to use. Though this is all true there are many things to think about when relying on 3-D printing as your manufacturing method for your 416 projects. Cost: 3-D printing is not a cost-effective way to produce parts if the product is to be mass manufactured. The filament though seems inexpensive, if you are making multiple design iterations on a part of significant size you can use up a spool quicker than you thought. A tip to use less material is to lower the density of the part so less filament is used to make a solid part. Also, you can make the parts hollow to further reduce material consumption. '''Lead-Time: '''Though 3-D printing is advertised as a rapid prototyping tool you will soon learn rapid is a relative term. Depending on the size, density and accuracy setting you choose to make your part the time to print can range from under an hour to over 24 hours. This is when you need to decide what is the purpose of the part you are printing and what are the minimum settings that will give you what you want in the shortest amount of time. Make sure if you choose to use this method to get started as soon as possible and expect delays due to the initial layer not sticking, machine break downs or other people in front of you. Delays happen, and it usually is a first come first serve basis which can hinder the ability to produce parts when you would like them. This can be a very handy manufacturing method when used correctly and in the correct manner. It is a prototyping tool and not a means on mass manufacturing due to its cost and lead time. If you choose to use this method, go talk to Kurt and have him review your design as he knows these machines and what they are capable of. Review what you need out of the part and relay the information to Kurt, so he can try and print your part in the quickest manner. Also, expect delays so plan for them accordingly so your project stays on track. When prototyping clients want to make sure that you understand the requirements are are expected. It can be confusing at times when you are pro typing you may want to just draw away and make any kind of design that comes to mind. But from experience I can say that clients want a clear communication that you fully know the expectations when it comes to first the spec doc and then of course the prototyping. As it comes to various prototypes, be aware that clients may ask for at least 3 designs that should all be equally put forth effort into. It was a struggle for our group as we put forth effort into one design and it was shown while we had to present them to the client. Just have confidence and know exactly what they expect describing how your design will advance their overall business. Category:ME 416 Help